Re: [RFC - doc] Add note about the possibility of symbols getting moved across blocks

[Siva Chandra <sivachandra@google.com>]

On Thu, Apr 26, 2012 at 7:43 PM, Eli Zaretskii <eliz@gnu.org> wrote:
> Maybe I simply miss something important here.  The text in question
> says this:
>
>   A @code{gdb.Block} is iterable.  The iterator returns the symbols
>   (@pxref{Symbols In Python}) local to the block.  Users using this
>   feature should keep in mind that future improvements to the internal
>   representation, of symbols and symbol tables, can move symbols across
>   blocks within a symbol table.
>
> Are you saying that future changes will prevent the possibility to
> get the symbols local to the block by iterating it?  That's not what
> the last sentence above seems to say.  It says that the symbols might
> be found in a different block, or something to that effect.  At least
> that's what I understand from reading it.  If my understanding is
> correct, how would my Python program that works today break with
> future versions of GDB?

This is my thought:  Take Tom's example of current 'globals' ending up
in a namespace block due to a future change.  Now, this is just an
example.  Meaning, a future existence of a namespace block is a
speculation now.  Since it is a speculation, it could eventually so
happen that we will not have a namespace block but something else or
nothing at all.  Hence, how things would change are unknown now, but
there is a chance that things will change.  What Doug and Tom are
trying to say is that, "It is OK to use the API now and for some time
in future, but keep an eye out for changes and change accordingly."
Also, since how things would change in future is unknown now, it is
probably not possible to specify now as to how exactly would a Python
program break in future.

AFAICT, if there is a change in future which can break an existing
Python program, or change the API behavior, then we mention this in
the docs and NEWS then. (?)

Thanks,
Siva Chandra
PS: I used the namespace block as an example and called it a
speculation.  It probably is not a speculation but a real plan!